1. Technical Field
The invention relates to a process for the preparation of high yields of 5-oxohexane nitriles. Such nitriles are formulated by catalytic conversion of a methyl ketone and an .alpha.,.beta.-unsaturated nitrile in the presence of a strong base.
One type of 5-oxohexane nitrile which can be created using the present process is 2,4-dimethyl-5-oxohexane nitrile.
2. Background Information
A related process is known from US patent specification U.S. Pat. No. 2,850,519. In particular, this publication describes the reaction of acrylic acid nitrile and ketones in the presence of primary amines as catalysts. It has appeared, however, that when asymmetrical methyl ketones are used in this process, as starting material in combination with other nitriles than acrylic acid nitrile (e.g. methacrylic acid nitrile), isomer mixtures are formed that contain a substantial amount of undesired isomer, namely the product of addition of the .alpha.,.beta.-unsaturated nitrile to the methyl group of the ketone, whereas this is not the case when acrylic acid nitrile is used as starting material in such a reaction. Furthermore, isolation of the isomers generally is very difficult.
As a consequence, the yield in which the 5-oxohexane nitriles can be obtained in purified form, that is, with less than 0.2 wt. % of undesired fisomer, generally is very low, as a major part of the nitrile is lost in the separation process.